The invention relates to an apparatus for continuous coating having a chamber wall, which forms a processing chamber, a thermal insulation which forms a processing area within the processing chamber, and a transportation device for substrates located in the processing area with a substrate transportation direction lying in the lengthwise extension of the apparatus for continuous coating. In this, the substrates overlie the side of the transportation device facing the substrate hereinafter referred to as the substrate side. Furthermore, the apparatus for continuous coating includes heating equipment, which heats the substrates.
There are known continuous coating apparatus, which essentially differ from high-vacuum coating apparatus in that they are used at relatively high pressures, i.e. pressures in the range of 1 to 10 mbar and work at high temperatures in the region of over 600° C. The relatively high pressure is preset using a special process gas.
As is known from high-vacuum coating apparatus, there is a transportation device in the processing area, with which it is possible to transport substrates along the length-wise extension of the continuous coating apparatus in one transportation direction. In this, the substrates pass through various processing stations. In such cases these processing stations can be separated from each other, so that separate individual processing areas are formed here.
In the case of traditional high-vacuum apparatus, thermal conduction and convection provide heat escape mechanisms, and convection, through the thermal insulation can be conveniently blocked by using radiation shields. In contrast to traditional high-vacuum coating apparatus, where the high vacuum performs a thermal insulating function, this function is dispensed with in the case of the continuous coating plants described above, which work with relatively high pressures. If, on account of a higher degree of gas pressure, the mechanisms of thermal conduction and convection additionally have an effect, insulation can take place both through radiation shields of a sufficiently high number, which have been set up accordingly and/or through thermal insulating materials. Consequently, thermal insulation is required to be installed on the inner side of the chamber wall, which prevents the escape of heat from the processing chamber or at least makes it more difficult for this to happen. Thermal insulation is in particular necessary at high temperatures, in order to keep the heat loss at a minimum. This thermal insulation therefore encloses the processing area. The high temperature is achieved in the processing area by using special heating equipment.
What is special about such an apparatus for coating is that a significant part of the material vapor generated in the processing area and let in for the coating of the substrate almost fills the entire processing area and a relatively good distribution of the material vapor of the substrate to be coated results inside the processing area. Consequently, vapor particles, which do not reach the substrate, are eliminated inside the processing area and lead to a contamination, for example, of the thermal insulation or even partly on the transportation device. Consequently, relatively short maintenance intervals are necessary.
In high-vacuum coating apparatus, it is common practice to cool parts, which undergo heating through the coating process, for example, the electrodes, by means of cooling elements. Any other use of these cooling elements is not known in the case of such coating apparatus. In continuous coating apparatus, which work at relatively high pressures of the kind cited earlier, the use of cooling elements was not known previously.
The invention is designed to fulfill the task of minimizing unwanted coating, in particular of parts of the apparatus, in order therefore to minimize the expense of maintaining and servicing the apparatus for continuous coating of the type cited in the beginning